RTX's [RTX] Raytheon and Lockheed Martin [LMT] have signed Memoranda of Understanding (MOU) with Italy's Avio SpA to help build a "state of the art" solid rocket motor (SRM) plant in the United States. Raytheon and Lockheed Martin will have "preferred access to a share of the Avio plant production capacity to meet future demand," according to Avio. Late last month, Avio said that its shareholders had approved a 10-year, $465 million transatlantic expansion plan geared to the production of…